Bug: random video stutters and freezes

[flapane]

As I wrote in the previous (and abandoned) thread, there aren't any signal issues at all (the antenna is brand new, and if I connect an LCD TV to the same antenna cable I'm using with this device, the video never stutters), but there often are random video stutters (mpeg SD or h264 HD, it's the same) even if the signal bar is in the green zone (SNR 24 to 26. I can see from my window the transmitters located some 3 miles from here) and no transmission errors are reported.
Furthermore, it started freezing every 30/60 minutes since 4 or 5 days, and I have to click on STOP and then click again on LIVE TV.
A "cold start" (ie. opening WinTV after Windows has just started) may be a hassle, because it will start reporting NO SIGNAL and you have to change channel several times before you can actually see the a/v stream.
Reinstalling WinTV and official drivers and updating audio/video/chipset drivers didn't help. I also tried a different USB cable.
Log attached for HVR900H 6600.

2012-07-12 20:59:54.051 [DEBUG][1] Stopping graph (and disabling now/next)
2012-07-12 20:59:54.081 [DEBUG][1] force file close()@1
2012-07-12 20:59:54.084 [DEBUG][1] force file close()@2
2012-07-12 20:59:54.084 [DEBUG][1] Stopping graph@2
2012-07-12 20:59:54.084 [DEBUG][1] Stopping graph@3
2012-07-12 20:59:54.106 [DEBUG][1] Stopping graph@4
2012-07-12 20:59:54.110 [DEBUG][1] Stopping graph@5

[flapane]

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